On 13-12-21, 13:46, Bard Liao wrote: > From: Ranjani Sridharan <ranjani.sridharan@xxxxxxxxxxxxxxx> > > This patch provides both a simplification of the suspend flows and a > better balanced operation during suspend/resume transition, as part of > the transition of Sound Open Firmware (SOF) to dynamic pipelines: the > DSP resources are only enabled when required instead of enabled on > startup. > > The exiting code relies on a convoluted way of dealing with suspend > signals. Since there is no .suspend DAI callback, we used the > component .suspend and marked all the component DAI dmas as > 'suspended'. The information was used in the .prepare stage to > differentiate resume operations from xrun handling, and only > reinitialize SHIM registers and DMA in the former case. > > While this solution has been working reliably for about 2 years, there > is a much better solution consisting in trapping the TRIGGER_SUSPEND > in the .trigger DAI ops. The DMA is still marked in the same way for > the .prepare op to run, but in addition the callbacks sent to DSP > firmware are now balanced. > > Normal operation: > hw_params -> intel_params_stream > hw_free -> intel_free_stream > > suspend -> intel_free_stream > prepare -> intel_params_stream > > This balanced operation was not required with existing SOF firmware > relying on static pipelines instantiated at every boot. With the > on-going transition to dynamic pipelines, it's however a requirement > to keep the use count for the DAI widget balanced across all > transitions. > > The component suspend is not removed but instead modified to deal with > a corner case: when a substream is PAUSED, the ALSA core does not > throw the TRIGGER_SUSPEND. This is problematic since the refcount for > all pipelines and widgets is not balanced, leading to issues on > resume. The trigger callback keeps track of the 'paused' state with a > new flag, which is tested during the component suspend called later to > release the remaining DSP resources. These resources will be > re-enabled in the .prepare step. > > The IPC used in the TRIGGER_SUSPEND to release DSP resources is not a > problem since the BE dailink is already marked as non-atomic. Acked-By: Vinod Koul <vkoul@xxxxxxxxxx> -- ~Vinod
